نتایج جستجو برای: sex chromosome abnormality
تعداد نتایج: 456037 فیلتر نتایج به سال:
Decrease in gamma-glutamyltransferase activity in early amniotic fluid in fetal trisomy 18 syndrome.
A study was carried out in which activity of gamma-glutamyl transpeptidase was measured in 259 samples of amniotic fluid obtained at various weeks of pregnancy. Two hundred and twenty-eight of the babies subsequently delivered had no chromosome abnormality and served as controls, while in 31 various chromosome abnormalities were detected. Mean activity of gamma-glutamyl transpeptidase in the co...
Introduction. The coexistence of Down and Turner syndromes due to double chromosome aneuploidy is very rare; it is even more rare to find the presence of a double monoclonal chromosomal abnormality. Objective. To report a unique case of double monoclonal chromosomal abnormality with trisomy of chromosome 21 and an X ring chromosome in all cells studied; no previous report has been found. Case R...
The X and Y chromosomes of placental and marsupial mammals originated from a pair of autosomes. Ohno hypothesised nearly 50 years ago that the expression levels of X-linked genes should be doubled to compensate for the degeneration of their Y-linked homologues during sex chromosome evolution. The advent of microarray and RNA (ribonucleic acid) sequencing technologies in the past decade prompted...
BACKGROUND Many different environmental and genetic sex-determination mechanisms are found in nature. Closely related species can use different master sex-determination switches, suggesting that these developmental pathways can evolve very rapidly. Previous cytological studies suggest that recently diverged species of stickleback fish have different sex chromosome complements. Here, we investig...
Sex chromosomes turn over rapidly in some taxonomic groups, where closely related species have different sex chromosomes. Although there are many examples of sex chromosome turnover, we know little about the functional roles of sex chromosome turnover in phenotypic diversification and genomic evolution. The sympatric pair of Japanese threespine stickleback (Gasterosteus aculeatus) provides an e...
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